Abstract |
The study area is located on the western flank of the Coteau des Prairie in Codington County, South Dakota. The lakes within the study area are all natural lakes of glacial origin, which were formed during the Wisconsin glaciation period. Photographic and thermal remote sensing imagery aided in the interpretation of chemical, geological, and biological features and events, but water quality-imagery correlations were largely unsuccessful. The majority of the lakes may be considered magnesium sulfate lakes with sodium becoming the more dominant cation in the more senescent lakes. Poor aquifer flushing, characteristic of closed drainage systems, resulted in an accumulation of 2153 mg/liter total dissolved solids in the ground water with an accumulation of sulfate which averaged 40% of the total dissolved solids by weight. With the exception of Grass Lake, the study lakes all occupy closed depressions with little or no ground-water movement between, and exist in various stages of senescence depending upon local climatic and edaphic conditions. Evaporation appears to be the principal cause of water loss and consequent mineralization. (Author) |